The beginning of power cable industry is usually attributed to the first New York City distribution system, created by Thomas Edison. This system used copper rods for the conductors. Fast development of industrial power grids in the twentieth century resulted in development of sophisticated engineering methods of power transmission using high current and high voltage power cables. Current state of the art power cables represent a highly optimized composition of wires made of low-resistivity metals, copper, aluminum and special alloys. Though low, the finite resistivity of such power cables leads to significant power losses in the power distribution and transmission lines. In the United States, estimated transmission and distribution losses are about 6%.
Recent advances in superconducting (SC) technology created new opportunities for developing new approaches to the power transmission and distribution. Low and high temperature superconductors were considered for various components of power grids, such as power switches, fault current limiters and AC transformers. Studies showed that low temperature superconductors cannot be feasibly used for commercial applications because the AC losses at cryogenic temperatures imply that the cryogenic cooling costs make the whole device uneconomic. On the other hand, the same kind of devices, made instead using high temperature superconductors (HTS), may be both practical and economically justifiable for the commercial utilization.
The most promising field for commercialization of HTS technology is its use for manufacturing power transmission and distribution cables. Several national and international projects with a goal of designing and integrating HTS power cables into experimental and existing power transmission systems are currently underway. Various HTS cable designs comprised of strands, or using Roebel, CORC and stacked tape structure, are being considered. Analytical and experimental studies show that HTS cables using CORC and stacked tape twisted topologies present better combinations of characteristics for power transmission and distribution.
One issue that arises when attempting to characterize the practicality of using these cables lies in design and implementation of the terminations, such as, for example, the connections of the SC cables to mate to normal conductor bus bars, as well as joints between two pieces of SC cables. The significance of the latter issue is due to the fact that superconducting filaments and tapes are produced in pieces, where the length of these pieces is limited by technical conditions and may be shorter than needed for a particular application. Various designs of HTS stacked tape terminations and joints have been presented. The peculiarity of these connections is that they are permanent. In other words, once made, these connections are not expected to be disconnected and reconnected afterwards.
Therefore, a system and method of creating connecting between sections of HTS cable that can be completed in the field would be beneficial. Further, it would be advantageous if these connections could be demountable, such that the pieces of the cable may be replaced or rearranged as needed.